What climate and shade does allspice need and can it grow in drier regions?

Allspice needs a warm humid tropical climate with good rainfall and prefers some shade when young, similar to the conditions that suit nutmeg and clove, so it does well in the humid Western Ghats and coastal belts and in warm humid hill foothills. It does not suit dry regions or cold areas, dry plains heat and low humidity are not favourable. So for a drier region the honest answer is that it is not well suited and you would struggle to get a good crop. If your area is warm and humid with reliable moisture, it can grow as a minor garden tree, but remember the Indian market is small. Match it to humid conditions, and if you are dry, choose a more suitable crop instead.